The present invention relates to a device and method for treatment of a dental cavity such as a root canal and, more particularly, but not exclusively to a device for sterilizing a root canal.
A root canal is the commonly used term for the main canals within the dentine of the tooth. These are part of the natural cavity within a tooth that consists of the dental pulp chamber, the main canals, and sometimes more intricate anatomical branches that may connect the root canals to each other or to the root surface of the tooth. Root canals are filled with a highly vascularized, loose connective tissue, the dental pulp. This sometimes becomes infected and inflamed, generally due to caries or tooth fractures that allow microorganisms, mostly bacteria from the oral flora or their byproducts, access to the pulp chamber or the root canals. The infected tissue is removed by a surgical intervention known as endodontic therapy, more commonly known as root canal treatment.
Removal and disinfection procedures are not always effective at removing individual bacteria, but it is even more difficult to remove bacterial films. Nevertheless complete removal of bacteria or sterilization of the canal prior to sealing the root canal is a necessary condition for a successful outcome to the treatment.
Known systems insert cleaning (disinfecting) fluids into the root canal but such fluids are highly toxic. Furthermore they have to be present in the root canal for a relatively large amount of time. In addition the fluid must reach every part of the root canal, something which cannot be guaranteed. In some cases, particularly where infection is already present, the treatment must be repeated several times before the root canal can be sealed. The method takes time and depends very much on the expertise of the dentist carrying out the treatment.
A further disadvantage of the above system is that bubbles or air pockets tend to occur, especially in the deeper parts of the root canal or where root canal passages are not straight, and the air pockets tend to prevent the cleaning fluid from making contact with all surfaces.
Other systems place an electrode inside the root canal and another electrode outside the tooth and pass a current between the two, closing the circuit via the human body. The electromagnetic field and in some case the temperature kills bacteria, but the effectiveness is limited because often the conditions in the canal are not ideal. This is particularly the case when the electrode is far from the apical aria. One version uses 500 Watts of power, at a frequency of 300-KHz, in order to create a current path from the apical aria of the root canal to the external electrode, through the patient's flesh. A disadvantage of this system is that much of the power provided goes to setting up the current path and not to carrying out the sterilization. Furthermore the sterilization effect is not uniform over the root canal, and requires exceptional skill on the part of the dentist in order to be successful. Furthermore the resistance provided by the human body varies between individuals, making it impossible to control the power level in given cases. Thus a higher than designed resistance may reduce the output and vice versa. Furthermore the power increases with proximity to the apical aria, due to the reduced distance between the two ends of the probe or electrode and in some cases a current overload may result, causing pain to the patient. Thus it is impossible to control the power and you may either expose the client to sharp, pain or you may fail to provide sufficient power to destroy all the bacteria.
In particular, efforts to ensure that the effect is evenly distributed over the root canal are complicated by the need to avoid the root canal apex. The apex contains healthy tissue which should not be damaged.
There is thus a widely recognized need for, and it would be highly advantageous to have, a method of root canal sterilization that is devoid of the above limitations.